#define  _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <algorithm>
#include <utility>
#include <functional>
#include <cstring>
#include <queue>
#include <stack>
#include <math.h>
#include <iterator>
#include <vector>
#include <string>
#include <set>
#include <math.h>
#include <iostream>
#include <random>
#include<map>
#include <iomanip>
#include <time.h>
#include <stdlib.h>
#include <list>
#include <typeinfo>
#include <list>
#include <set>
#include <cassert>
#include<fstream>
#include <unordered_map>
#include <cstdlib>
#include <complex>
#include <cctype>
#include <bitset>
using namespace std;
typedef string::const_iterator State;
#define Ma_PI 3.141592653589793
#define eps 1e-5
#define LONG_INF 2000000000000000000LL
#define GOLD 1.61803398874989484820458
#define MAX_MOD 1000000007LL
#define GYAKU 500000004LL
#define MOD 998244353LL
#define seg_size 262144*2
#define REP(a,b) for(long long a = 0;a < b;++a)
int main() {
#define int long long
	int query;
	cin >> query;
	REP(te, query) {
		long long a, b, c;
		cin >> a >> b >> c;
		if (c == 1) {
			cout << -1 << endl;
			continue;
		}
		vector<long long> inputs;
		while (a != 0) {
			inputs.push_back(a % c);
			a /= c;
		}
		reverse(inputs.begin(), inputs.end());
		long long ans = inputs.size()-1;
		for (int i = 0; i < inputs.size(); ++i) {
			if (inputs[i]) ans++;
		}
		if (inputs[0] == 1 && inputs[1] <= c - 2&&inputs[1] != 0) {
			ans--;
		}
		cout << ans * b << endl;
	}
}